Bump flask from 1.0.2 to 2.3.2 in /utils/google_app_engine (#11465)

Bumps [flask](https://github.com/pallets/flask) from 1.0.2 to 2.3.2.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](https://github.com/pallets/flask/compare/1.0.2...2.3.2)

---
updated-dependencies:
- dependency-name: flask
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

utils/google_app_engine/additional_requirements.txt

@@ -1,5 +1,5 @@
 # add these requirements in your app on top of the existing ones
 pip==21.1
-Flask==1.0.2
+Flask==2.3.2
 gunicorn==19.10.0
 werkzeug>=2.2.3 # not directly required, pinned by Snyk to avoid a vulnerability